Using Interactive, Temporal Visualizations for WWW-based Presentation and Exploration of Spatio-Temporal Data

In recent years, spatio-temporal data are increasingly recorded in database-enabled information systems. To share the beneet, often, a public data access is provided utilizing WWW-based visual interfaces. If spatio-temporal data are queried, data visualization and exploration in a spatial and temporal context is needed to better present and analyze spatio-temporal behaviours and relationships. In existing WWW-based interfaces of temporal geographical information or scientiic data visual-ization systems, only videos, static visualizations (images) or, recently, VRML-worlds (Virtual Reality Modeling Language) are applied which support neither 3D-nor temporal navigation, respectively. Additionally, these interfaces ooer only small support for further exploratory tools according to the temporal domain and to conceptual database entities which users are often aware of. In this paper, we propose an extension to VRML which supports the description of spatio-temporal (temporal 3D-)graphics and entities by integrating the valid time dimension and the entity concept. This is realized by a set of new VRML-nodes representing temporal geometries, time references and database entities and a set of interactive visualization techniques extending standard VRML-browsers to perform temporal navigation and to further explore the visualization during presentation. One result of this proposal is that a new type of visualizations, i.e. interactive, temporal visualizations (animations), can be generated, stored in les, integrated in Web-pages and explored spatially and temporally by interaction or animation. This is demonstrated by two decision support applications from water management and urban planning.